mycroft holmes
Last Activity: 9 Years ago
mn+1 is divisible by 3 and 8.
If mn+1 is divisible by 3, you can easily see that we need m and n to be of the form 3s+1 and 3t-1 or vice versa. So m+n is divisible by 3
If mn+1 is divisible by 8, then either m and n are of the form 8s+1 and 8t-1 in some order, or 8s-3,8t+3 . Again m+n is divisible by 8
So, m+n is divisible by 3 and 8 and hence by 24